"Google has released a research paper that suggests C++ is the best-performing programming language in the market. The internet giant implemented a compact algorithm in four languages - C++, Java, Scala and its own programming language Go - and then benchmarked results to find 'factors of difference'."

I tend to agree that it's not usually worth optimizing code in assembly, however GCC's code is often less efficient than it should be.

Examples?

We as programmers can do a better job than GCC at anticipating certain states and algorithmic conditions which give GCC trouble. Under these circumstances, it's not all that difficult to beat it.

Certainly we programmers can do a better job given that we understand the overall purpose of the code much better than any compiler, however I very much disagree with it 'not being all that difficult to beat it', you certainly need to be a very good assembly programmer to do so.

Expert programmers who are both well-versed in assembly and the things they are solving with it will certainly atleast equal and most often beat a compiler. Case in point would be encoders like x264 etc, they are full with hand-optimized assembly which easily beat the generated output of both GCC, ICC, LLVM etc when disabling the hand-optimized assembly and relying entirely on compiler optimization. But these guys are very good assembly programmers and experts at what they are trying to implement using it, this is hardly the norm amongst programmers. Hence very few programmers out there can actually beat the optimized output of compilers.